1. Field of the Invention
This invention generally relates to power transmission means and, more particularly, to a novel endless belt assembly having a connector with improved holding capabilities.
2. Description of Related Art
The advent of extruded lengths of polymeric materials has been accompanied by efforts to adapt to such materials to endless belt applications. A number of fastening means were available for the purpose of connecting two free ends of other types of belting together to form a continuous length. Such methods, however, left much to be desired when applied to tubing. Specifically these fastening means normally required special equipment and techniques that were difficult to apply on equipment where there was little room to work and where the belt had to be formed in situ.
U. S. Pat. Nos. 3,461,733 and 3,501,971 disclose major improvements in such connectors for endless belt applications using polymeric tubing. The former patent discloses a novel connector in combination with a tough elastomer belt. The connector comprises a central shank or shaft and outwardly facing gripping heads extending from the end of the shaft. Each gripping head has a conoidal or pyramidal shape. The latter patent discloses improvements in such connectors that include a belt-seizing rib for improving the bite between the connector and the tubing. In general the inventions disclosed in those patents have been highly successful.
Yet the experience gained with extended use of such connectors has identified some limitations. First, an upper load limit exists for a given tubing material This load limit lies below the tension requirements for a number of applications. Secondly, a number of new materials could be applied to endless belt construction. However, these connectors have not worked successfully with such materials. Thus, potential applications for endless belts exist that the prior inventions have not been able to satisfy.
U.S. Pat. No. 3,922,759 discloses two embodiments of a connector comprising a gripping member which is easily flexed away from the direction of entry into tubing to facilitate such entry. In one embodiment the gripping member is molded; in another, the connector comprises discrete pieces. The molded coupling insert comprises gripping heads integrally formed at the extremes of a central cylindrical body. The gripping heads comprise fluted gripping rings or integral annular flanges. One of the flanges is flexible with respect to the axis of the central cylinder body. The ring is also tapered to facilitate insertion of the connector into a belt. After insertion, when tension is applied to the belt assembly, the biting ring formed by such a flange flexes outwardly or forwardly until it intercepts an outer stop ring and bites into the belt. In the alternate construction, a internally threaded cylinder body receives machine screws and flex washers. The flex washers are radially divided to form flexible segments that flex toward the direction of the cylinder when the connector is being inserted into the tube and flex outward into a biting engagement with the tubing material when tension is applied.
This approach achieved its objectives of improving load characteristics and ease of insertion. However, it was found that the increased holding power realized with these connectors did not justify associated increased manufacturing costs. As a result, connectors, such as shown in U.S. Pat. Nos. 3,461,733 and 3,501,971, have continued to be the connectors of choice for endless belt applications. This acceptance continues despite the load limit and material limitations that foreclose a number of applications for endless belts formed of polymeric tubing.